Viral Occlusion Research Articles

Morphology and development of an occluded virus from the black-soil scarab, Othnonius batesi

Particles of a virus occluded in spheroidal protein crystals, similar to those of Vagoiavirus melolonthae of Melolontha melolontha, have been found in Othnonius batesi (Scarabaeidae: Melolonthinae) collected from Glen Innes, New South Wales, Australia. Macroscopic and microscopic disease signs were noted. The structure of virus particles within protein crystals has been studied by electron microscopy. A developmental cycle for the virus is proposed, based on observations of thin sections of fat body taken from living diseased specimens. We propose that viruses of this type should be called “spheroidosis viruses”.

A polyhedrosis in Culex salinarius of Louisiana

Free and occluded virus particles found in the cytoplasm of the midgut epithelial cells of second-instar larvae of Anopheles quadrimaculatus averaged 60 and 66 nm in diameter, respectively. Spherical crystals containing these particles averaged 133 nm in diameter while cuboidal crystals averaged 156 nm. The crystals showed a macromolecular paracrystalline lattice typical of polyhedral protein. In a few instances, the cuboidal crystals appeared to have coalesced to form larger crystals. The observations suggest that the free particles and their occluded forms may represent stages of a cytoplasmic polyhedrosis virus.